Enhanced oral bioavailability of dexibuprofen by a novel solid Self-emulsifying drug delivery system (SEDDS)

The main objective of this study was to prepare a solid form of lipid-based self-emulsifying drug delivery system (SEDDS) by spray drying liquid SEDDS with an inert solid carrier Aerosil 200 to improve the oral bioavailability of poorly water-soluble drug dexibuprofen. The liquid SEDDS was a system that consisted of dexibuprofen, Labrasol, Capryol 90 and Labrafil M 1944 CS. The particle size analysis revealed no difference in the z-average particle diameter of the reconstituted emulsion between liquid and solid SEDDS. The solid SEDDS was characterized by SEM, DSC and XRD studies. In vivo results of solid SEDDS and dexibuprofen powder in rats at the dose of 10 mg/kg showed that the initial plasma concentrations of drug in solid SEDDS were significantly higher than those of dexibuprofen powder (P < 0.05). The solid SEDDS gave significantly higher AUC and Cmax than did dexibuprofen powder (P < 0.05). In particular, the AUC of solid SEDDS was about twofold higher than that of dexibuprofen powder. Our results suggested that this solid SEDDS could be used as an effective oral solid dosage form to improve the bioavailability of poorly water-soluble drug dexibuprofen.     

口服干乳剂研究进展

干乳剂是新型的药物载体传递系统，理化稳定性好，再分散性好，能显著改善难溶性药物的溶出，增加体外释放，促进肠吸收，提高口服生物利用度。对近年来国外文献以喷雾干燥法制备干乳剂的最新研究进展，该文做了主要概述，表明喷雾干燥乳剂作为一种含油的粉末制剂，其应用前景广阔。     

Solid self-nanoemulsifying drug delivery system (S-SNEDDS) for oral delivery of glimepiride: development and antidiabetic activity in albino rabbits

Abstract

Context: This study presents novel self-nanoemulsifying drug delivery system potential of oral delivering which leads poorly aqueous soluble drug glimepiride.

Objective: The objective of this study was to prepare solid self-nanoemulsifying drug delivery system (S-SNEDDS) for the improved oral delivery of glimepiride and to evaluate its therapeutic efficacy in albino rabbits.

Results and discussion: The droplet size analyses revealed a droplet size of less than 200?nm. The solid state characterization of S-SNEDDS by scanning electron microscopy (SEM), X-ray powder diffraction and differential scanning calorimetry (DSC) revealed the absence of crystalline glimepiride in the S-SNEDDS. The in vitro dissolution studies revealed that the significant improvement in glimepiride release characteristics. The effect of S-SNEDDS on therapeutic efficacy of glimepride was assessed in albino rabbits by monitoring blood glucose levels and compared with free drug suspension, L-SNEDDS. The S-SNEDDS showed significant (p?<?0.05) increase in in vitro drug release and therapeutic efficacy as compared with free drug.

Conclusion: This study demonstrated that S-SNEDDS is a promising novel drug delivery system of glimepride to enhance oral delivery.     

Solid self-nanoemulsifying drug delivery system (SNEDDS) for enhanced oral bioavailability of poorly water-soluble tacrolimus: physicochemical characterisation and pharmacokinetics

Abstract

To develop a novel self-nanoemulsifying drug delivery system (solid SNEDDS) with better oral bioavailability of tacrolimus, the solid SNEDDS was obtained by spray-drying the solutions containing the liquid SNEDDS and colloidal silica. Its reconstitution properties were determined and correlated to solid state characterisation of the powder. Moreover, the dissolution and pharmacokinetics in rats was done in comparison to the commercial product. Among the liquid SNEDDS formulations tested, the liquid SNEDDS comprised of Capryol PGMC, Transcutol HP and Labrasol (10:15:75, v/v/v) presented the highest dissolution rate. In the solid SNEDDS, this liquid SNEDDS was absorbed in the pores and attached onto the surface of the colloidal silica. Drug was present in the amorphous state in it. The solid SNEDDS with 5% w/v tacrolimus produced the nanoemulsions and improved the oral bioavailability of tacrolimus in rats. Therefore, this solid SNEDDS would be a potential candidate for enhancing the oral bioavailability of tacrolimus.     

Solid super saturated self-nanoemulsifying drug delivery system (sat-SNEDDS) as a promising alternative to conventional SNEDDS for improvement rosuvastatin calcium oral bioavailability

ABSTRACT

Objective: This study aims to illustrate the applicability of solid supersaturated self-nanoemulsifying drug delivery system (sat-SNEDDS) for the improvement of rosuvastatin calcium (RC) oral bioavailability.

Methods: Different sat-SNEDDS were prepared by incorporating different ratios of RC into SNEDDS using tween80/PEG400 (77.2%) as surfactant/cosurfactant mixture and garlic /olive oil (22.8%) as oil phase. The prepared systems were characterized viz; size, zeta potential, TEM and stability. Various hydrophilic and hydrophobic carriers were employed to solidify the optimized RC sat-SNEDDS. The influence of the carrier was investigated by SEM, XRPD, DSC, flow properties, in vitro precipitation, drug release and oral bioavailability study.

Results: The adsorption of the stable positively charged nanocarrier RC sat-SNEDDS onto solid carriers provided free flowing amorphous powder. The carrier could amend the morphological architecture and in vitro release of the RC solid sat-SNEDDS. Hydrophobic carriers as microcrystalline cellulose 102 (MCC) showed superior physical characters and higher dissolution rate over hydrophilic carriers as maltodextrin with respective T_100% 30 min and 45 min. The rapid spontaneous emulsification, the positively nanosized MCC-sat-SNEDDS improved oral bioavailability of RC by 2.1-fold over commercial tablets.

Conclusion: Solid MCC-sat-SNEDDS combined dual benefits of sat-SNEDDS and solid dosage form was successfully optimized to improve RC oral bioavailability.     

Development of a high-throughput in vitro intestinal lipolysis model for rapid screening of lipid-based drug delivery systems

PurposeTo develop a high-throughput in vitro intestinal lipolysis (HTP) model, without any means of pH-stat-titration, to enable a fast evaluation of lipid-based drug delivery systems (LbDDS).Material and methodThe HTP model was compared to the traditionally used dynamic in vitro lipolysis (DIVL) model with regard to the extent of lipid digestion and drug distribution of two poorly soluble model drugs (cinnarizine and danazol), during digestion of three LbDDS (LbDDS I–III).ResultThe HTP model was able to maintain pH around 6.5 during digestion, without the addition of NaOH to neutralize the free fatty acids (FFAs), due to an increased buffer capacity. Cinnarizine was primarily located in the aqueous phase during digestion of all three LbDDS and did not differ significantly between the two models. The distribution of danazol varied from formulation to formulation, but no significant difference between the models was observed. The triacylglycerides (TAG) in LbDDS III were digested to the same extent in both models, whereas the TAG present in LbDDS II was digested slightly less in the HTP model. No TAG was present in LbDDS I and digestion was therefore not analyzed.ConclusionThe HTP model is able to predict drug distribution during digestion of LbDDS containing poorly water soluble drugs in the same manner as the DIVL model. Thus the HTP model might prove applicable for high-throughput evaluation of LbDDS in e.g. 96 well plates or small scale dissolution equipment.     

Effects of solid carriers on the crystalline properties, dissolution and bioavailability of flurbiprofen in solid self-nanoemulsifying drug delivery system (solid SNEDDS)

In order to investigate the effects of solid carriers on the crystalline properties, dissolution and bioavailability of flurbiprofen in a solid self-nanoemulsifying drug delivery system (solid SNEDDS), different solid SNEDDS formulations were prepared by spray-drying the solutions containing liquid SNEDDS and various carriers. The liquid SNEDDS, composed of Labrafil M 1944 CS/Labrasol/Trasncutol HP (12.5/80/7.5%) with 2% w/v flurbiprofen, gave a z-average diameter of about 100 nm. Silicon dioxide, a hydrophobic solid carrier, produced an excellent conventional solid SNEDDS with a nanoemulsion droplet size of less than 100 nm, similar to the liquid SNEDDS and smaller than the other solid SNEDDS formulations. The drug was in an amorphous state in this solid SNEDDS. Furthermore, it greatly improved the dissolution rate and oral bioavailability of flurbiprofen in rats because it allowed the spontaneous formation of an interface between the oil droplets and the water. Magnesium stearate, a hydrophobic carrier, produced a solid SNEDDS with the largest diameter. However, it greatly enhanced the dissolution rate and oral bioavailability due to the formation of a simple eutectic mixture. The hydrophilic carriers such as polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (Na-CMC) and hydroxypropyl-β-cyclodextrantrin (HP-β-CD) did not form a solid SNEDDS but rather a solid dispersion (or microcapsule). HP-β-CD improved the dissolution rate but did not improve the oral bioavailability as much as the hydrophobic polymers. PVA and Na-CMC hardly improved the dissolution rate but maintained constantly high plasma levels in rats for a long period. Thus, the selection of carrier is an important factor in the development of solid SNEDDS, since the carriers had significant effects on the crystalline properties, dissolution and oral bioavailability of flurbiprofen and on the formation of solid SNEDDS.     

A novel solid self-nanoemulsifying drug delivery system (S-SNEDDS) for improved stability and oral bioavailability of an oily drug, 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol

To develop a novel solid self-nanoemulsifying drug delivery system (S-SNEDDS) for a water-insoluble oily drug, 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) with improved stability and oral bioavailability, numerous S-SNEDDS were prepared with surfactant, hydrophilic polymer, antioxidant, and calcium silicate (porous carrier) using the spray-drying method. Their physicochemical properties were evaluated using emulsion droplet size analysis, SEM and PXRD. Moreover, the solubility, dissolution, stability, and pharmacokinetics of the selected S-SNEDDS were assessed compared with the drug and a commercial soft capsule. Sodium lauryl sulfate (SLS) and hydroxypropyl methylcellulose (HPMC) with the highest drug solubility were selected as surfactant and hydrophilic polymer, respectively. Among the antioxidants tested, only butylated hydroxyanisole (BHA) could completely protect the drug from oxidative degradation. The S-SNEDDS composed of PLAG/SLS/HPMC/BHA/calcium silicate at a weight ratio of 1:?0.25:?0.1:?0.0002:?0.5 provided an emulsion droplet size of less than 300?nm. In this S-SNEDDS, the drug and other ingredients might exist in the pores of carrier and attach onto its surface. It considerably improved the drug stability (about 100 vs. 70%, 60?°C for 5?d) and dissolution (about 80 vs. 20% in 60?min) compared to the commercial soft capsule. Moreover, the S-SNEDDS gave higher AUC, C_max, and T_max values than the commercial soft capsule; in particular, the former improved the oral bioavailability of PLAG by about 3-fold. Our results suggested that this S-SNEDDS provided excellent stability and oral bioavailability of PLAG. Thus, this S-SNEDDS would be recommended as a powerful oral drug delivery system for an oily drug, PLAG.     

Development of a biocompatible creatinine-based niosomal delivery system for enhanced oral bioavailability of clarithromycin

Context: Nonionic surfactant vesicles have gained increasing scientific attention for hydrophobic drugs delivery due to their biocompatibility, stability and low cost.

Objective: The aim of the present study was to synthesize and evaluate a novel creatinine-based nonionic surfactant in terms of its ability to generate biocompatible niosomal system for the delivery of Clarithromycin.

Materials and Methods: The surfactant was synthesized by reacting creatinine with lauroyl chloride followed by characterization using ¹HNMR and MS. The drug-loaded niosomal vesicles of the surfactant were characterized for drug encapsulation efficiency (EE) using LC-MS, vesicle size using dynamic light scattering (DLS) and vesicle shape using atomic force microscopy (AFM). The surfactant was also investigated for blood hemolysis, in vitro cytotoxicity against different cell lines and in vivo acute toxicity in mice. Furthermore, the in vivo bioavailability of Clarithromycin encapsulated in the novel niosomal formulation was investigated using rabbits and quantified through validated LC-MS/MS method.

Results and discussion: Findings showed that vesicles were able to entrap up to 67.82?±?1.27% of the drug, and were rounded in shape with a size around 202.73?±?5.30?nm and low polydispersity. The surfactant caused negligible blood hemolysis, very low cytotoxicity and was found to be safe up to 2500?mg/kg body weight using mice. The niosomal formulation showed twofold enhanced oral bioavailability of Clarithromycin as compared to commercial formulations of the drug.

Conclusion: The study has shown that the creatinine-based niosomes developed in our laboratory were biocompatible, safe and increased the oral bioavailability of the model hydrophobic Clarithromycin using experimental animals.     

Development of optimized self-nano-emulsifying drug delivery systems (SNEDDS) of carvedilol with enhanced bioavailability potential

Carvedilol, a widely prescribed cardiovascular drug for hypertension and congestive heart failure, exhibits low and variable bioavailability owing to poor absorption and extensive hepatic first-pass metabolism. The current research work, therefore, entails formulation development of liquid self-nano-emulsifying drug delivery systems (SNEDDS) to enhance the bioavailability of carvedilol by facilitating its transport via lymphatic circulation. The formulation constituents, i.e. lipids, surfactants, and co-surfactants, were selected on the basis of solubility studies. Pseudo-ternary phase diagrams were constructed to embark upon the selection of blend of lipidic (i.e. Capmul PG8) and hydrophilic components (i.e. Cremophor EL as surfactant and Transcutol HP as co-surfactant) for efficient and robust formulation of SNEDDS. The SNEDDS, systematically optimized employing a central composite design (CCD), were evaluated for various response variables viz drug release parameters, emulsification time, emulsion droplet size, and mean dissolution time. In vitro drug release studies depicted that the release from SNEDDS systems followed a non-Fickian kinetic behavior. The TEM imaging of the optimized formulation affirmed the uniform shape and nano size of the system. Accelerated studies of the optimized formulation indicated high stability of the formulation for 6 months. The in situ perfusion studies carried out in wistar rats construed several fold augmentation in the permeability and absorption potential of the optimized formulation vis-à-vis marketed formulation. Thus, the present studies ratified the potential of SNEDDS in augmenting the oral bioavailability of BCS class II drugs.     

QbD-based systematic development of novel optimized solid self-nanoemulsifying drug delivery systems (SNEDDS) of lovastatin with enhanced biopharmaceutical performance

Abstract

Of late, solid self-nanoemulsifying drug delivery systems (S-SNEDDS) have been extensively sought-after owing to their superior portability, drug loading, stability and patient compliance. The current studies, therefore, entail systematic development, optimization and evaluation (in vitro, in situ and in vivo) of the solid formulations of (SNEDDS) lovastatin employing rational quality by design (QbD)-based approach of formulation by design (FbD). The patient-centric quality target product profile (QTPP) and critical quality attributes (CQAs) were earmarked. Preformulation studies along with initial risk assessment facilitated the selection of lipid (i.e. Capmul MCM), surfactant (i.e. Nikkol HCO-50) and co-surfactant (i.e. Lutrol F127) as CMAs for formulation of S-SNEDDS. A face-centered cubic design (FCCD) was employed for optimization using Nikkol-HCO50 (X₁) and Lutrol-F127 (X₂), evaluating CQAs like globule size, liquefaction time, emulsification time, MDT, dissolution efficiency and permeation parameter. The design space was generated using apt mathematical models, and the optimum formulation was located, followed by validation of the FbD methodology. In situ SPIP and in vivo pharmacodynamic studies on the optimized formulation carried out in unisex Wistar rats, corroborated superior drug absorption and enhanced pharmacodynamic potential in regulating serum lipid levels. In a nutshell, the present studies report successful QbD-oriented development of novel oral S-SNEDDS of lovastatin with distinctly improved biopharmaceutical performance.     

Self-microemulsifying drug delivery system for improving the bioavailability of huperzine A by lymphatic uptake

Huperzine A (Hup-A) is a poorly water-soluble drug with low oral bioavailability. A self-microemulsifying drug delivery system (SMEDDS) was used to enhance the oral bioavailability and lymphatic uptake and transport of Hup-A. A single-pass intestinal perfusion (SPIP) technique and a chylomicron flow-blocking approach were used to study its intestinal absorption, mesenteric lymph node distribution and intestinal lymphatic uptake. The value of the area under the plasma concentration–time curve (AUC) of Hup-A SMEDDS was significantly higher than that of a Hup-A suspension (P<0.01). The absorption rate constant (K_a) and the apparent permeability coefficient (P_app) for Hup-A in different parts of the intestine suggested a passive transport mechanism, and the values of K_a and P_app of Hup-A SMEDDS in the ileum were much higher than those in other intestinal segments. The determination of Hup-A concentration in mesenteric lymph nodes can be used to explain the intestinal lymphatic absorption of Hup-A SMEDDS. For Hup-A SMEDDS, the values of AUC and maximum plasma concentration (C_max) of the blocking model were significantly lower than those of the control model (P<0.05). The proportion of lymphatic transport of Hup-A SMEDDS and Hup-A suspension were about 40% and 5%, respectively, suggesting that SMEDDS can significantly improve the intestinal lymphatic uptake and transport of Hup-A.     

Development and optimisation of atorvastatin calcium loaded self-nanoemulsifying drug delivery system (SNEDDS) for enhancing oral bioavailability: in vitro and in vivo evaluation

The objective of this study was to develop and optimise self-nanoemulsifying drug delivery system (SNEDDS) of atorvastatin calcium (ATC) for improving dissolution rate and eventually oral bioavailability. Ternary phase diagrams were constructed on basis of solubility and emulsification studies. The composition of ATC–SNEDDS was optimised using the Box–Behnken optimisation design. Optimised ATC–SNEDDS was characterised for various physicochemical properties. Pharmacokinetic, pharmacodynamic and histological findings were performed in rats. Optimised ATC–SNEDDS resulted in droplets size of 5.66?nm, zeta potential of ?19.52?mV, t₉₀ of 5.43?min and completely released ATC within 30?min irrespective of pH of the medium. Area under the curve of optimised ATC–SNEDDS in rats was 2.34-folds higher than ATC suspension. Pharmacodynamic studies revealed significant reduction in serum lipids of rats with fatty liver. Photomicrographs showed improvement in hepatocytes structure. In this study, we confirmed that ATC–SNEDDS would be a promising approach for improving oral bioavailability of ATC.     

Lipid - An emerging platform for oral delivery of drugs with poor bioavailability

The sole objective of pharmaceutical science is to design successful dosage forms which fulfill the therapeutic needs of the patients effectively. Development of new drug entities is posing real challenge to formulators, particularly due to their poor aqueous solubility which in turn is also a major factor responsible for their poor oral bioavailability. Lipids as carriers, in their various forms, have the potential of providing endless opportunities in the area of drug delivery due to their ability to enhance gastrointestinal solubilization and absorption via selective lymphatic uptake of poorly bioavailable drugs. These properties can be harvested to improve the therapeutic efficacy of the drugs with low bioavailability, as well as to reduce their effective dose requirement. The present communication embodies an in-depth discussion on the role of lipids (both endogenous and exogenous) in bioavailability enhancement of poorly soluble drugs, mechanisms involved therein, approaches in the design of lipid-based oral drug delivery systems with particular emphasis on solid dosage forms, understanding of morphological characteristics of lipids upon digestion, in vitro lipid digestion models, in vivo studies and in vitro-in vivo correlation.     

Improved understanding of the effect of food on drug absorption and bioavailability for lipophilic compounds using an intestinal pig perfusion model

The purpose of this study was to investigate the relative importance of mechanisms behind the effect of food on the intestinal absorption and bioavailability for low solubility compounds by applying a porcine single-pass perfusion model. Nanoparticle suspensions of the model compounds, danazol and cyclosporine were perfused through the jejunum in isotonic fluid alone (control) and isotonic fluid with a P-glycoprotein (P-gp) inhibitor (verapamil) or dietary and endogenous lipids added. The drugs were also administered as saturated solutions in the isotonic fluid containing lipids. Administration of cyclosporine together with verapamil increased the absorption compared to the control (1.6 times) suggesting an effect on jejunal permeability. However, addition of dietary lipids to the media led to a 50% reduction in the absorption of cyclosporine indicating lack of major effects by P-gp inhibition by lipids in vivo. The absorption of danazol was increased (2.6 times) when administered as a nanosuspension in lipid containing media compared to the control, but decreased (60%) when administered as a solution in the same media. This shows how important dissolution of the drug nanoparticles is in drug absorption. The difference in the effect of lipids in the absorption of cyclosporine and danazol when administered as nanosuspensions may be due to different distribution to the colloidal structures present in the media, thereby rendering the drugs’ different diffusion rates in the perfused segment. In conclusion, solubilisation seems to be a more important factor than P-gp inhibition as an explanation for the food–drug interaction observed for several low solubility drugs. In addition, the partition into different colloidal structures seems to play a major role in the dissolution and absorption of poorly soluble drugs.     

Trans-resveratrol self-nano-emulsifying drug delivery system (SNEDDS) with enhanced bioavailability potential: optimization,pharmacokinetics and in situ single pass intestinal perfusion (SPIP) studies

Abstract

Trans-resveratrol (t-RVT) is a potent antioxidant. By virtue of extensive pre-systemic metabolism and existence of enterohepatic recirculation, t-RVT bioavailability is almost zero. The current study aimed to develop self-nanoemulsifying drug delivery systems (SNEDDS) using long-chain triglycerides (LCTs) of t-RVT in an attempt to circumvent such obstacles. Equilibrium solubility studies indicated the choice of Lauroglycol FCC as lipid, and of Labrasol and Transcutol P as surfactants, for formulating the SNEDDS. Ternary phase diagrams were constructed to select the areas of nanoemulsions, and the amounts of lipid (X₁) and surfactant (X₂) as the critical factor variables. The SNEDDS were optimized using 3² central composite design (CCD) and the optimized formulation (OPT) located using overlay plot. The nanometer size range and high negative values of zeta potential depicted non-coalescent nature of the SNEDDS. Optimized formulation indicated marked improvement in drug release profile vis-à-vis pure drug. Cloud point determination and accelerated stability studies ascertained the stability of OPT. Augmentation in the values of K_a (3.29-fold) and AUC (4.31-fold) indicated significant enhancement in the rate and extent of bioavailability by the OPT compared with pure drug. In situ perfusion (SPIP) studies in Wistar rats construed remarkable enhancement in the absorptivity and permeability parameters of SNEDDS vis-à-vis the pure drug. Successful establishment of level A of in vitro/in vivo correlation substantiated the judicious choice of the in vitro dissolution milieu for simulating the in vivo conditions. The present study, therefore, reports the successful development of SNEDDS with distinctly enhanced bioavailability of t-RVT.     

A novel hybrid delivery system: Polymer-oil nanostructured carrier for controlled delivery of highly lipophilic drug all-trans-retinoic acid (ATRA)

Many recently developed drugs encounter delivery issues due to their high lipophilicity and poor aqueous solubility. This study reports the development of a novel hybrid nanocarrier known as polymer-oil nanostructured carrier (PONC), in which highly lipophilic drugs such as all-trans-retinoic acid (ATRA) and indomethacin pre-solubilized in oil phase were dispersed in a polymeric matrix of poly(d,l-lactic-co-glycolic acid) (PLGA). In comparison to the standard PLGA only nanoparticles, PONC substantially increased the encapsulation efficiency of ATRA and indomethacin by up to 259% and 124%, respectively. Differential scanning calorimetry analysis revealed that the inclusion of oil introduced nanostructure into the polymeric matrix of the carrier. This feature facilitated more uniform distribution of the drug molecules which subsequently led to improved drug release kinetics with significantly reduced burst release effects (p<0.05). PONC was lyophilizable, remained physically stable when stored at low temperatures, and demonstrated low non-specific carrier toxicity. Delivery of ATRA by PONC also significantly improved its anticancer activity over the standard PLGA only nanoparticles (p<0.05). Our findings have therefore validated a promising delivery system that integrates the advantages of lipid-based (e.g. efficient encapsulation of highly lipophilic drugs) and polymeric colloidal carriers (e.g. uniform size, good stability), plus potential therapeutic benefits for delivery of poorly water-soluble anticancer drugs like ATRA.     

Preparation,in vitro and in vivo evaluation of solid-state self-nanoemulsifying drug delivery system (SNEDDS) of vitamin A acetate

Vitamin A self-nanoemulsifying drug delivery system (SNEDDS), which comprises soybean oil, Cremophor EL, and Capmul MCM-C8, was prepared and mixed with different grades of Avicel to produce homogenized powders. The resultant powders were compressed into tablets. The prepared tablets were characterized for their thickness, hardness, friability, disintegration time, and dissolution rate. In addition, the relative bioavailability of the tablets in comparison to solid-state Vitamin A oily solution (SSVAOS) tablets was investigated in rats. Vitamin A dissolution rate was markedly different from one formulation to another. From the bioavailability data, it was observed that Vitamin A SNEDD tablets have higher bioavailability (relative bioavailability 143.68%) compared with SSVAOS tablets. The AUC and C_max of Vitamin A SNEDD tablets were found to be significantly different from that of SSVAOS tablets.     

Process optimization of a novel production method for nanosuspensions using design of experiments (DoE)

Particle size reduction is a suitable method to enhance the bioavailability of poorly soluble drugs. The reduction effectiveness depends on compound properties like crystallinity, hardness and morphology. Sometimes, it is difficult to obtain small particles. To solve this problem a combinative method was developed: a combination of freeze drying with high pressure homogenization (so-called H 96 process). The freeze drying modifies the drug structure to obtain a brittle, fragile starting material for the subsequent homogenization step. Screening experiments with glibenclamide have shown a relation between the lyophilization conditions and the final particle size. Systematic investigations using design of experiment (DoE) were conducted to identify optimal process parameters. The influence of the independent variables drug concentration and organic solvent composition during freeze drying were tested by conducting a two factorial design of experiment. The model drug was dissolved in mixtures of dimethyl sulfoxide (DMSO) and tert-butanol (TBA) in different concentrations, freeze dried and subsequently homogenized at high pressure. Using optimized process conditions the particle size after 20 cycles was very small: 164 nm (z-average) and 0.114 μm (d50%). On the contrary, with unmodified drug the results were 772 nm (z-average) and 2.686 μm (d50%). It was shown, that the structure modification of the drug by means of freeze drying can significantly improve the particle size reduction effectiveness of high pressure homogenization. The study confirmed also the usefulness of DoE for nanocrystal production.     

Evaluation of potential of Zn-pectinate gel (ZPG) microparticles containing mesalazine for colonic drug delivery

BACKGROUND AND THE PURPOSE OF THE STUDY: Pectin derivatives have been utilized for colonic drug delivery (CDD). In this study the effects of different formulation variables upon the characteristics of pectinate microparticles (MPs) prepared by ionotropic gelation technique for colonic delivery of mesalazine was investigated. METHODS: In-vitro drug release of MPs was studied using USP XXIV dissolution apparatus type I, in different fluids e.g. simulated gastric fluid (SGF: pH 1.2), simulated intestinal fluid (SIF: pH 7.4), and simulated colonic fluid (SCF: pH 6.8) of volume 900 ml, at 100 rpm maintained at 37±0.2°C. This study was also performed in the presence of 4% w/v rat caecal content (RCC) using phosphate buffer saline (pH 6.8) as SCF. Gamma scintigraphy study was performed on New Zealand rabbit animal model using (99m) Tc. RESULTS: The results showed that maximum entrapment of mesalazine (86.1±1.7%) and strength of gel network zinc pectinate gel microparticles (ZPGD2) was achieved in cross-linking solution of pH 1.6. Batch of ZPGD2 showed least swelling ratio and drug release. In RCC medium the t(50%) value of CPG-MPs was 3-4 folds greater than ZPG-MPs. Scintigram showed the residence of ZPG-MPs (filled in enteric coated capsule) in colon more than 9 hrs and delivery of almost all the drug loading dose in colon. MAJOR CONCLUSION: The results of this study suggest the designed formulation of ZPG-MPs has the potential to serve as a colonic drug delivery system.